Question

public function process(Zend_Controller_Request_Abstract $request)
{
     $this->first_name = $this->sanitize($request->getPost('first_name'));
....
}

My question is $request is an instance of class zend_controller_request_abstract, but getpost is a function defined in class zend_controller_request_http which extends zend_controller_request_abstract, so why does $request invoke getPost() directly?

Answer 1

The type hint is just that, a hint. All it states is that $request must extend from Zend_Controller_Request_Abstract. It does not mean that $request is an instance of Zend_Controller_Request_Abstract.

In this particular case, $request is an instance of Zend_Controller_Request_Http which does implement getPost() and so you can call $request->getPost() with no problems. $request is also an instance of a class that extends from Zend_Controller_Request_Abstract and so PHP allowed it to be passed into the process method in the first place.